1. Field of Invention
The present invention relates to machine vision systems and, more specifically, to a system and method for determining the nature of a test tube and associated cap using optical imaging techniques.
2. Background of the Art
Machine vision plays an important role in automated and robotic systems, such as assembly line manufacturing, quality control inspection, and sample processing. Conventional systems are generally comprised of an optical imager, such as a charged coupled device (CCD) or similar device using digital imaging technology, that is positioned to capture images of objects that pass in front of it. In low-light or enclosed applications, machine vision systems may include an illumination source, such as a bank of light emitting diodes (LEDs), positioned proximately to the imager. The images are subsequently processed to decode information contained in the resulting two-dimensional image, such as 1D linear codes, 2D stacked/matrix codes, OCR fonts, and postal codes. The image captured by the machine vision system may also be subjected to more advanced processing, such as shape recognition or detection algorithms, that provide information about the object of interest in the image. However, the characteristics of digital images taken by machine vision systems, such as the contrast of the image, often limit the processing techniques that may be employed and adversely affects the accuracy of the results obtained from the processing of the image contents.
In sample handling systems, such as blood analyzers and the like, samples are moved to and from diagnostic modules for automatic testing and retesting using a loading rack that holds a plurality of carriers, such as test tubes filled with samples. Proper identification of the samples, decoding of information encoded into labels on the test tube, recognition of the test tube type, and even determining whether the tube contains a cap may be critical for timely and accurate processing of samples.